The present invention relates to a retaining device, and more particularly to a retaining device for a power drill shaft. The retaining device enables to lock the power drill shaft so that when electricity is not provided to the power drill, the power drill is able to be operated manually.
An electrical tool, such as an electric drill, normally is powered by electricity from an electrical outlet or a rechargeable battery. However, no matter which kind of power the power drill is used, once the electricity is off due to a power failure or a battery malfunction, the power drill is useless. Somehow, even when the power is off, the worker still has to catch up the schedule. Under such a situation, the worker will have to manually operate the power drill. When manually operating the power drill, because the driving gear of the motor shaft is directly mated with a gear assembly and the gear assembly is then mated with the driven gear, the driven gear will drive the motor shaft to rotate simultaneously, which causes the bit or the screw driver mounted on the front of the power drill to be unable to fulfill the desired goal.
Furthermore, when changing the bit of the power drill, the worker will have to use a clutch key to rotate the clutch which is mounted directly with the output shaft of the power drill, so that the worker will have to use one hand to firmly hold the head of the clutch and the other hand to rotate the clutch key, which causes a great deal of inconvenience to the worker.
To overcome the shortcomings, the present invention intends to provide an improved retaining device to mitigate or obviate the aforementioned problems.
The primary objective of the invention is to provide a retaining device for a power drill shaft. The retaining device has multiple brake shoes selectively driven by a driving disk, such that when the power is off, the brake blocks will be driven by a cam operated by an output shaft to lock the power drill shaft.
Another objective of the invention is that the outer faces of the brake shoes have patterns, so that when the brake shoes abut the inner face of the housing for receiving the brake shoes, the friction between the brake shoes and the inner face of the housing is increased so as to provide a good braking effect to the output shaft of the power shaft.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.